Multipart zip archive, each part being extractable separately

[floyd6]

So basically each part has to be a new zip file which can be extracted independently from the other parts. The size of each part would be 5mb (naturally this way no files can be split between the parts but that's ok since I'm not going to pack files bigger than 5mb). I've been looking for an appropriate option in winrar, winzip , 7-zip but I couldn't find one. Any ideas except doing it by hand e.g. with total commander by adding files to an archive making sure its size does not exceed the limit?